There are two free plugins which can enable multiple BuddyPress networks. I would recommend that you wait until either has been upgraded for BP 1.7
– https://wordpress.org/extend/plugins/bp-multi-network/ – shared userbase across networks but don’t know if you can activate on per site basis
– http://buddydev.com/plugins/buddypress-multi-network/installation/ –
you can activate BP per subsite and userbase per site is not saved
Best thing is to ask the respective plugin devs for more info.
Good luck
